I just cut a project with a similar workflow to the first one above but with one variation. I left my project at 4K and used the proxy media setting. I had no trouble with playback on an i7 Macbook Pro, just had to wait out the background rendering of the proxy media.
I have a question about your resolve workflow. Does this relink the original R3D files? If not, is there a way to modify the XML file before importing into resolve to link the R3D files? I assume a find and replace may be in order but don't know until I look at the XML file.